Skip adding default content-type header 'application/x-www-form-urlencoded' if content is null #1083

Dear ScribeJava,

Library: https://github.com/scribejava/scribejava/tree/master/scribejava-httpclient-apache

While building the request object:

I would like to ask you add a condition while adding the default 'Content-Type' header while preparing the requests, to verify the entity and if it's null then skip adding default 'Content-Type' header

private <T> Future<T> doExecuteAsync(String userAgent, Map<String, String> headers, Verb httpVerb,
            String completeUrl, HttpEntity entity, OAuthAsyncRequestCallback<T> callback,
            OAuthRequest.ResponseConverter<T> converter) {
        final RequestBuilder builder = getRequestBuilder(httpVerb);
        builder.setUri(completeUrl);

        if (entity != null && httpVerb.isPermitBody()) {
            if (!headers.containsKey(CONTENT_TYPE)) {
                builder.addHeader(CONTENT_TYPE, DEFAULT_CONTENT_TYPE);
            }
            builder.setEntity(entity);
        }

just like the implementation of OkHttpClient lib:

I agree with your reasoning from #966, that you want to allow the possibilities. On the other hand, few servers are too strict that they don't accept other kinds of 'Content-Type' that they don't support.

If you still want to keep the behavior same, I would like to understand the reasoning behind a different implementation for OkHttpClient.